If it were me, there wouldn't have been any nude (or otherwise compromising) pictures on the phone in the first place. I know, hindsight is always 20-20.
This isn't 1963 anymore. More information than we ever dreamed is readily available to anyone who looks around for it. She is, in some ways, responsible for allowing this to happen.
If she can find somebody with deep enough pockets, maybe she can sue for some payback. Or, she could do something really creative and, and blast this story out onto social media.
If she has access to his Facebook account, for example, she can make her case a matter of public record.
It's not like the kid who did it could retaliate by blackmailing her with the pictures, they're already out there. He took his best shot at her, and now she gets to return the favor.
Colleges and prospective employers do check social media, and this might give those colleges and prospective employers reason to wonder if they want to invite such a slimy little rat to join with them.
I understand your position and agree that isn’t something someone should do, personally.
But there are laws against invasion of privacy, but there are none that I know of that govern stupidity. What that little sh!t did was invasion of privacy and he knew better. And she should go after the owners of the phone and the account over which the stolen information was disseminated. Let the parents deal with the recrimination against the errant minor.